Climate Science

Historical Carbon Uptake

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Science  25 Oct 2013:
Vol. 342, Issue 6157, pp. 403
DOI: 10.1126/science.342.6157.403-c

The high levels of atmospheric CO2 that have resulted from fossil fuel burning and other anthropogenic activities over the past 150 years are expected to cause increased uptake of carbon by the terrestrial biosphere over the next century, thereby partially offsetting some of the CO2 emissions. This effect is difficult to quantify, though. Deforestation and other land-use changes have transferred great quantities of carbon from the biosphere to the atmosphere since preindustrial times, making the magnitude of carbon uptake by land plants difficult to infer. Shevliakova et al. address this issue with a coupled climate–carbon cycle model study of the terrestrial carbon sink, paying special attention to how land use has changed since the beginning of the industrial revolution. They estimate that enhanced vegetation growth over that period reduced atmospheric CO2 concentration by 85 ppm below what it would have been without that effect, thereby avoiding approximately 0.3°C of warming. This represents a dramatic shift of the carbon budget, by more than 250 billion tons of carbon—more than 30 years of emissions at current rates.

Proc. Natl. Acad. Sci. U.S.A. 110, 16730 (2013).

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